Method of making edgelay material

ABSTRACT

A novel composite edgelay material has a thin strip of a first metal secured to an edge of a strip of another base metal. The thin metal strip extends along the edge of the base metal strip as an edgelay and is preferably coextensive with the edge surface of the base metal strip. However, the edgelay strip is secured to the base metal edge surface only along a thin stripe which is of a width less than the width of the base metal edge surface. This novel composite material is made in a novel method in which a metal wire or rod is disposed with a thin stripe extending along the wire or rod periphery in engagement with the edge surface of the base metal strip. The wire or rod is then resistance welded to the base metal edge and, preferably, is deformed to a different cross-sectional configuration such as a rectangular cross-sectional configuration coextensive with the base metal strip edge surface.

United States Patent [45] Patented [73} Assignee Dec. 2 l 1971 Texas Instruments Incorporated Dallas, Tex.

[54] METHOD OF MAKING EDGELAY MATERIAL 5 Claims, 5 Drawing Figs.

52 use! 29/480,

29/497.s, 219/83 51 Int.Cl ..B23k3l/02 5o] FieldofSearch 29/480 3,3 84,958 5/1968 Christian et a1 29/498 X 3,456,332 7/1969 Belalou et a1. 29/497.5 X 3,499,211 3/1970 Dubuc 29/480 Primary Examiner-John F. Campbell Assistant Examiner Ronald J. Shore Att0rneys-Har0ld Levine, Edward J. Connors, .lr., John A.

Haug, James P. McAndrews and Gerald B. Epstein ABSTRACT: A novel composite edgelay material has a thin strip of a first metal secured to'an edge of a strip of another base metal. The thin metal strip extends along the edge of the base metal strip as an edgelay and is preferably coextensive with the edge surface of the base metal strip. However, the edgelay strip is secured to the base metal edge surface only along a thin stripe which is of a width less than the width of the base metal edge surface. This novel composite material is made in a novel method in which a metal wire or rod is disposed with a thin stripe extending along the wire or rod periphery in engagement with the edge surface of the base metal strip. The wire or rod is then resistance welded to the base metal edge and, preferably, is deformed to a different cross-sectional configuration such as a rectangular cross-sectional configuration coextensive with the base metal strip edge surface.

PATENTEUnmznen 3528235 Inventors: Joseph A. Willough b y, ,Brz'an R.Ruark,

b C M 111M531.

METHOD OF MAKING EDGELAY MATERIAL In the manufacture of certain electrical contact members and the like, a strip of precious metal is secured to a face of a strip of base metal extending along the length of the base metal strip. This composite strip material is then cut transversely of its length to form individual electrical contact members each of which has a small precious metal surface portion to serve as a low resistance electrical contact surface. When this contact surface is to be formed at the edge of the base metal strip as is required in some applications, a composite strip material called an edgelay material is used. It is found however that it is difficult to form such edgelay materials in an economical manner. In one known process in which the edgelay is soldered to the edge of the base metal, the process is limited to the choice of certain solders and solderable metal combinations and requires at least a certain thickness of the precious edgelay material to be successfully soldered, which thickness may be more than is required for the purposes of the application. In another known process, alternate layers of base metal and precious metal are roll bonded together and the precious metal layers are then slit to form several base metalprecious metal bars. Each bar is then rolled to produce the desired elongated edgelay material of smaller gauge or thickness. In this process, the base metal-precious metal bond is frequently inadequate, material loss during slitting is high, and the process is expensive and frequently requires minimum thicknesses of precious metal which are greater than are actually required for application purposes.

It is an object of this invention to provide a novel and improved composite, edgelay material; to provide such a composite material in which the edgelay is securely attached to the base metal; to provide such a composite material in which the edgelay is relatively thinner than has previously been possible; to provide a novel and improved method for making such composite edgelay material; and to provide such a method which is conveniently and economically performed to produce improved composite edgelay material at relatively lower cost than has previously been possible.

Briefly described, the novel and improved method of this invention comprises the steps of disposing a wire or rod of a first metal such as a precious metal along an edge of an elongated, relatively wide and thin base metal strip so that a thin stripe extending along the periphery of the wire or rod engages the edge surface of the base metal strip. The wire or rod is then resistance welded to the base metal edge surface along this line or stripe engagement. Preferably, the wire or rod is then deformed, as by passing the composite wire-strip material through a rolling mill or the like, for changing the cross-sectional configuration of the wire attached to the base metal edge surface. For example, a round wire attached to the base metal edge surface is preferably deformed to the cross-sectional configuration of a thin rectangular metal strip, the thin strip being coextensive with the base metal edge surface and being welded to the base metal edge surface along a thin line or stripe of engagement extending generally along the center of the base metal edge surface.

Other objects, advantages, and details of the improved edgelay material and improved process of making said edgelay material in accordance with this invention appear in the following detailed description of preferred embodiments of the invention, the detailed description referring to the drawings in which:

FIG. 1 is a partial perspective view of a strip of composite edgelay material known in the prior art;

FIG. 2 is a diagrammatic view illustrating the novel and improved method provided by this invention for making composite edgelay material;

FIG. 3 is a section view to enlarged scale along line 33 of FIG.2;

FIG. 4 is a section view to enlarged scale along line 4-4 of FIG. 2 illustrating the novel composite edgelay material of this invention; and

FIG. 5 is a section view similar to FIG. 4 illustrating an alternate embodiment of the composite edgelay material and method of this invention.

Referring to the drawings, 10 in FIG. 1 illustrates a composite edgelay material known in the prior art in which an edgelay 12 of a precious metal or the like is secured along an edge of a base metal strip 14, the edgelay being coextensive with the edge surface of the base metal edge surface as indicated at 16 in FIG. 1. As will be understood, this composite edgelay material can be cut transversely of its length as indicated by the dotted line I7 in FIG. 1 to form individual electrical contact members each of which has a small portion of the edgelay material disposed at the end of the contact member to serve as a low-resistance electrical contact surface. As noted above, in such prior art edgelay materials, the thickness r of the edgelay was frequently required by process limitations to be greater than was actually required for the application of contact members made from the edgelay strip material. Further, the bond formed at 16 between the edgelay and base metal portions of the composite material was frequently inadequate.

In accordance with this invention, a novel and improved composite edgelay material 18, as illustrated particularly in FIGS. 2 and 4 is formed by advancing a metal wire or rod 20 form a supply reel (not shown) and by advancing an elongated, relatively wide and thin metal strip 22 into engagement with each other so that the wire or rod is disposed to extend generally along the center of an edge surface of the metal strip with the peripheral surface of the wire or rod in line or stripe engagement with the center portion of the edge of the metal strip. The wire or rod, preferably formed of a precious metal such as silver, gold, silver alloy or gold alloy or the like, is then resistance welded to the edge of the metal strip along the thin line or stripe of engagement between the wire or rod and the edge surface of the strip.

For example, in a preferred embodiment of this invention, the wire 20 is formed of fine silver and the strip 22 is formed of a base metal such as brass having a composition of approximately 70 percent copper and 30 percent zinc by weight. As illustrated in FIGS. 2 and 3, the wire 20 is advanced between resistance welding rolls 24 and 26 together with the base metal strip 22 so that the wire and strip are continuously brought into engagement with each other at the welding rolls, the rolls then pressing the wire and strip together and directing electrical current from one of the rolls through the wire and strip materials to the other welding roll, thereby to heat the wire and strip materials at the area of engagement therebetween and to weld the wire and strip together in the conventional manner of resistance welding. For example, where the fine silver wire 20 has a diameter of 0.022 inches and the brass strip has a width of 0.4375 and a thickness of 0.040 inches, the wire and strip are pressed together with a force of about 400 pounds per square inch and a current of 25 amperes at 440 volts is directed between the rolls 24 and 26 to form the resistance weld 32 between the wire and strip as illustrated in FIG. 3. As will be understood, the resistance welding roll 24 is preferably provided with an accurate surface 24.! to engage a substantial surface of the wire 20 whereas the wire makes only theoretical line engagement with the edge surface 34 of the base metal strip. Similarly, the welding roll 26 is provided with a flat surface 26.] for making engagement with a substantial surface of the base metal strip 22. In this way, current directed between the rolls through the wire and strip is readily controlled to heat and weld the wire at the location 32 without tending to stick the wire or strip to the welding rolls.

In accordance with this invention, the welded, composite wire-strip material is then preferably advanced from the resistance welding rolls and is passed through deforming rolls wherein the wire 20 is deformed to a different cross-sectional configuration. For example, in a preferred embodiment of this invention, the welded composite material is passed between a pair of pressure rolls 28 wherein the wire 20 is deformed to the cross-sectional configuration of a thin rectangular strip which is coextensive in area with the edge surface of the base metal strip to which the wire is attached, the thin strip configuration to which the wire is deformed being welded to the base metal strip only along the thin weld line or stripe 32. That is, the

deformed wire is not welded to the full surface area of the base metal strip edge surface. In deforming the wire in this manner, the wire and base metal strip are engaged by respective rolls 28 which squeeze the wire and strip together from either side of the weld 32, the rolls 28 cooperating with a pair of guide rolls 30 which retain the thickness of the base metal strip 22 at substantially its original dimension during deformation of the wire 20.

In this method, it is found that a relatively small diameter wire is easily and securely attached to the edge of a base metal strip and is easily deformed to produce a composite edgelay material having a very thin edgelay portion. Where the edgelay wire 20 is formed of a precious metal as is frequently the case, this means that the thickness of the edgelay material can be tailored to the application of the edgelay material and does not require any extra thickness in the edgelay portion merely for process reasons. In fact, as is illustrated in FIG. 5, if an exceedingly thin precious metal edgelay is required in a composite edgelay material 35, the solid metal wire 20 is readily replaced with a composite metal wire 36 having a metal core 38 and a metal cladding 40 metallurgically bonded together in a conventional manner, the composite metal wire 36 being resistance welded, as at 44, in the manner described to a base metal strip 42 of brass or the like. As will be understood, the composite wire 36 is then easily deformed to a different cross-sectional configuration if desired. In this arrangement, the cladding 40 of the composite wire is desirably formed of a precious metal such as silver whereas the core 38 is formed of a base metal such as the brass embodied in the strip 42. After deformation of the composite wire in the manner described, the composite wire cladding forms a very thin layer of the precious metal at the edge of the base metal strip.

It should be understood that although the edgelay wires 20 and 36 have been described as embodying precious metals which are relatively softer than the base metals of the strips 22 and 42, the composite edgelay material of this invention is easily formed of any weldable metal materials within the scope of this invention. Further, although the wires 20 and 36 are shown as being of round configuration to facilitate obtaining line engagement with the base metal strip edge surface and to facilitate obtaining greater area of engagement with the welding roll 24, rods or wires of other cross-sectional configurations could also be used within the scope of this invention. For example, the wire 20 could be of square cross-sectional configuration and could be disposed to engage a corner edge of such a wire configuration with the base metal strip edge surface. In addition, the wire seam welded to the base strip could be deformed into other than rectangular cross-sectional configuration and could, for example, be deformed into a triangu- 1. A method of making a composite edgelay material in the form of an elongate, relatively wide and thin composite metal strip which principally embodies a first metal material but which has a lateral portion extending along an edge of the strip formed of a second metal material, which composite strip material is useful in making a plurality of members, such as electrical contact members each having a major portion.

formed of said first metal and an end portion of said second metal, by repeatedly cutting said composite strip material transversely of the length of said composite strip material, said method comprising the steps of continuously advancing an elongate, relatively wide and thin strip of one metal material and an elongate rod of other metal material against each other to form a narrow line of engagement between said rod and a thin lateral edge surface of said metal strip with said line of engagement extending longitudinally along said rod and longitudinally along the center of said thin lateral edge surface of said metal strip, continuously pressing said rod against said lateral edge surface of said metal strip and directing electrical current between said rod and metal strip through said engaged portions thereof for resistance welding said rod to said lateral edge surface of said metal strip continuously along said line of engagement, and deforming said metal rod to engage said lateral edge surface of said metal strip coextensive with said lateral edge surface to form said composite edgelay material.

2. A method as set forth in claim 1 wherein said rod is formed of a precious metal selected from the group consisting of silver, gold silver alloys and gold alloys and wherein said metal strip is formed of a metal selected from the group consisting of base metals weldable to said selected precious metal.

3. A method as set forth in claim 2 wherein said rod is formed of silver and said metal strip is formed of brass.

4. A method as set forth in claim 1 wherein said rod comprises a composite rod material having a metal core and having a cladding metallurgically bonded to said core.

5. A method as set forth in claim 4 wherein said composite rod comprises a core of brass having a cladding of silver metallurgically bonded to said core, said metal strip being formed of brass.

i t i t 

1. A method of making a composite edgelay material in the form of an elongate, relatively wide and thin composite metal strip which principally embodies a first metal material but which has a lateral portion extending along an edge of the strip formed of a second metal material, which composite strip material is useful in making a plurality of members, such as electrical contact members each having a major portion formed of said first metal and an end portion of said second metal, by repeatedly cutting said composite strip material transversely of the length of said composite strip material, said method comprising the steps of continuously advancing an elongate, relatively wide and thin strip of one metal material and an elongate rod of other metal material against each other to form a narrow line of engagement between said rod and a thin lateral edge surface of said metal strip with said line of engagement extending longitudinally along said rod and longitudinally along the center of said thin lateral edge surface of said metal strip, continuously pressing said rod against said lateral edge surface of said metal strip and directing electrical current between said rod and metal strip through said engaged portions thereof for resistance welding said rod to said lateral edge surface of said metal strip continuously along said line of engagement, and deforming said metal rod to engage said lateral edge surface of said metal strip coextensive with said lateral edge surface to form said composite edgelay material.
 2. A method as set forth in claim 1 wherein said rod is formed of a precious metal selected from the group consisting of silver, gold silver alloys and gold alloys and wherein said metal strip is formed of a metal selected from the group consisting of base metals weldable to said selected precious metal.
 3. A method as set forth in claim 2 wherein said rod is formed of silver and said metal strip is formed of brass.
 4. A method as set forth in claim 1 wherein said rod comprises a composite rod materiAl having a metal core and having a cladding metallurgically bonded to said core.
 5. A method as set forth in claim 4 wherein said composite rod comprises a core of brass having a cladding of silver metallurgically bonded to said core, said metal strip being formed of brass. 